Conventional communication systems, such as telephony systems, typically employ a billing system through which a subscriber or user of the telephony system is billed for any charge-incurring use made of the telephony system. In current telephony systems billing is typically performed on either a post-pay or a pre-paid basis.
In post-pay systems, charge-incurring calls made through the telephony system by a subscriber are collated over a fixed period, such as a month, and the subscriber is invoiced for all charge-incurring use made since the previous invoice was received. In this way the subscriber pays for charge-incurring use made of the telephony system after the use has occurred.
In pre-paid systems, a subscriber maintains a credit in subscriber account, and before any charge-incurring use may be made of the telephony system the balance of the subscriber account is checked. Charge-incurring use may typically only be made whilst the subscriber has a positive account balance. In this way the subscriber pays in advance prior to any charge-incurring use of the telephony system occurring.
In pre-paid systems it is desirable for the subscriber account balance to be updated in substantially real-time so that the account balance held in the billing system accurately accounts for all charge-incurring use made of the telephony system by the subscriber. Any delay in doing so can lead, for example, to unscrupulous subscribers making fraudulent use of the telephony system.
It is also becoming desirable for accounting in post-paid systems to also be performed in substantially real-time, thereby enabling a subscriber to consult, at any time, for example via the Internet, the current billing amount accrued during an accounting period.
Many such conventional billing systems are so-called intelligent network (IN) systems using, for example, SS7 and other IN protocols. Such IN systems were predominantly designed for the billing of charge-incurring telephone voice calls, and are hereinafter referred to as legacy IN billing systems.
Over recent years many new non-voice call services have been introduced by telephony system operators in addition to the ability to make and receive traditional telephone voice calls. For example, in the world of mobile telephony, short message system (SMS) messaging enables subscribers to send and receive short text-based messages. More recent services include data network access services, multimedia messaging (MMS), to name but a few.
The introduction of such new services creates new revenue models for telephony system operators. Some services, such as SMS, are billed on an event basis, whereby each SMS message sent by a subscriber is billed at a predetermined amount. Use of other services, such as access to data networks, is typically billed on a usage basis such as the length of time a connection to a data service is maintained or the amount of data downloaded. Such services may also be billable using a value approach enabling, for example, a file to be downloaded for a predetermined cost, irrespective of the download time or the file size.
Legacy IN billing systems, as mentioned above, were initially designed for the billing of telephone voice calls and are not generally suitable, nor easily adaptable, to handle the billing of the aforementioned new services. Although telephony system operators could upgrade their legacy IN billing systems to newer billing systems which can handle the billing of such new services, the financial investment already made in such legacy IN billing systems deters many operators from doing so. Thus, for the network operators it is desirable to be able use to existing legacy IN billing systems for the billing of new services.
One recently developed technique for billing SMS messages using a legacy IN billing system is for the telephony system to simulate a telephone call on behalf of the subscriber each time a SMS message is sent. Such a simulated call generates IN signaling messages which are sent between a switch and an IN billing system, in the same manner as the IN messages which are exchanged between a switch and an IN billing system when a conventional telephone voice call is made. However, such a simulated call does not lead to the establishment of any trunk connectivity or voice path.
The simulated call is made to a called party number having a predetermined billable rate, and the simulated call lasts for an appropriate duration such that, at the end of the call, the billing amount charged to the subscriber by way of the simulated call equals the amount the network operator wishes to charge for sending of the SMS message. In this way, the billing is achieved by way of a simulated call, thereby enabling legacy billing systems to be used for the billing of some non-telephone call services.
However, one problem with this approach is that a simulated call is made each time use is made of a non-telephone call service. Whilst the simulated call is active, resource is being consumed by both telephony system and the legacy IN billing system, for example since a billing signaling message session is maintained until the simulated call is terminated.
Whilst the duration of such a simulated call may be in the order of several tens of seconds for a low-cost SMS message, the duration may be substantially longer when using other services generating a higher-cost billing amount. Such higher-cost services include sending a premium rate SMS message, downloading a film or music file, and the like. For example, if a subscriber downloads a large software application this may involve a data connection lasting anything from a few seconds up to many tens of minutes or more, and may involve the downloading of large amounts of data. If the telephony system generates a simulated call for billing the use of the data service, this will typically involve a simulated call having a duration substantially the same length of time as the data connection or data transfer. Such a system, whilst indeed enabling billing for such services to be achieved using legacy billing system, uses substantially resources of the telephony system.
A further problem is that the longer a telephone call lasts the greater the probability that the simulated call will be dropped due to network problems, thereby leading to a potential loss of revenue for the telephony system operator. The potential existence of such problems makes it desirable to add in mechanism to handle such eventualities, thereby further increasing the complexity of such systems.
Accordingly, one aim of the present invention is to overcome, or at least alleviate, at least some of the aforementioned problems.